小口径可膨胀波纹管水力膨胀过程的数值模拟与试验研究

Numerical simulation and experiment on hydraulic expansion process of expandable liners for small diameter boreholes

为了确保可膨胀波纹管在120mm地质钻井中实现封隔漏失地层的功能,在合理设计8字形波纹管截面形状的基础上,采用有限元理论模拟了不同壁厚和材料的波纹管水力膨胀成形过程,并进行了室内水力膨胀试验。结果表明:波纹管壁厚越薄,膨胀效果越好,但壁厚必须满足抗外挤强度和抗内压强度条件;适用于120mm井眼的8字形波纹管,其材质应符合如下条件。屈强比≤0.6;延伸率≥25%;抗拉强度σb≥410 MPa;试制的波纹管膨胀后最小外径能够满足后续机械膨胀要求,最大膨胀压力为13.6MPa,符合钻探现场使用条件。研究结果为波纹管野外试验提供了技术支撑。

In order to ensure the sealing function of expandable liners inΦ120mm boreholes,based on the proper design of an“8”shape section corrugated pipe,the hydrodynamic expansion forming process of the corrugated pipe with different wall thickness and materials is simulated by using the finite element theory,and the indoor hydrodynamic expansio n test is carried out.Under the condition of satisfying the extrusion strength and internal pressure strength,the thinner the wall thickness of liners,the better the expansion effect;the“8”shape section liners suitable forΦ120 mm boreholes should meet the following conditions:yield ratio≤0.6,elongation≥25%,tensile strengthσb≥410MPa;the minimum diameter of the liners after expansion can meet the requirements of subsequent mechanical expansion,and the maximum expansion pressure is 13.6MPa,which meets the requirements of drilling site operation.This provides technical support for field test of the liners.